6 research outputs found
Attacks in Stream Ciphers: A Survey
Nowadays there are different types of attacks in block and stream ciphers. In this work we will present some
of the most used attacks on stream ciphers. We will present the newest techniques with an example of usage in
a cipher, explain and comment. Previous we will explain the difference between the block ciphers and stream
ciphers
D.STVL.7 - Algebraic cryptanalysis of symmetric primitives
The recent development of algebraic attacks can be considered an important breakthrough in the analysis of symmetric primitives; these are powerful techniques that apply to both block and stream ciphers (and potentially hash functions). The basic principle of these techniques goes back to Shannon's work: they consist in expressing the whole cryptographic algorithm as a large system of multivariate algebraic equations (typically over F2), which can be solved to recover the secret key. Efficient algorithms for solving such algebraic systems are therefore the essential ingredients of algebraic attacks. Algebraic cryptanalysis against symmetric primitives has recently received much attention from the cryptographic community, particularly after it was proposed against some LFSR- based stream ciphers and against the AES and Serpent block ciphers. This is currently a very active area of research. In this report we discuss the basic principles of algebraic cryptanalysis of stream ciphers and block ciphers, and review the latest developments in the field. We give an overview of the construction of such attacks against both types of primitives, and recall the main algorithms for solving algebraic systems. Finally we discuss future research directions
Automated Design Space Exploration and Datapath Synthesis for Finite Field Arithmetic with Applications to Lightweight Cryptography
Today, emerging technologies are reaching astronomical proportions. For example, the Internet
of Things has numerous applications and consists of countless different devices using different
technologies with different capabilities. But the one invariant is their connectivity. Consequently,
secure communications, and cryptographic hardware as a means of providing them, are faced
with new challenges. Cryptographic algorithms intended for hardware implementations must be
designed with a good trade-off between implementation efficiency and sufficient cryptographic
strength. Finite fields are widely used in cryptography. Examples of algorithm design choices
related to finite field arithmetic are the field size, which arithmetic operations to use, how to
represent the field elements, etc. As there are many parameters to be considered and analyzed, an
automation framework is needed.
This thesis proposes a framework for automated design, implementation and verification of finite
field arithmetic hardware. The underlying motif throughout this work is “math meets hardware”.
The automation framework is designed to bring the awareness of underlying mathematical
structures to the hardware design flow. It is implemented in GAP, an open source computer algebra
system that can work with finite fields and has symbolic computation capabilities. The framework
is roughly divided into two phases, the architectural decisions and the automated design genera-
tion. The architectural decisions phase supports parameter search and produces a list of candidates.
The automated design generation phase is invoked for each candidate, and the generated VHDL
files are passed on to conventional synthesis tools. The candidates and their implementation results
form the design space, and the framework allows rapid design space exploration in a systematic
way. In this thesis, design space exploration is focused on finite field arithmetic.
Three distinctive features of the proposed framework are the structure of finite fields, tower field
support, and on the fly submodule generation. Each finite field used in the design is represented as
both a field and its corresponding vector space. It is easy for a designer to switch between fields
and vector spaces, but strict distinction of the two is necessary for hierarchical designs. When an
expression is defined over an extension field, the top-level module contains element signals and
submodules for arithmetic operations on those signals. The submodules are generated with
corresponding vector signals and the arithmetic operations are now performed on the coordinates.
For tower fields, the submodules are generated for the subfield operations, and the design is generated
in a top-down fashion. The binding of expressions to the appropriate finite fields or vector spaces
and a set of customized methods allow the on the fly generation of expressions for implementation
of arithmetic operations, and hence submodule generation.
In the light of NIST Lightweight Cryptography Project (LWC), this work focuses mainly on small
finite fields. The thesis illustrates the impact of hardware implementation results during the design
process of WAGE, a Round 2 candidate in the NIST LWC standardization competition. WAGE
is a hardware oriented authenticated encryption scheme. The parameter selection for WAGE was
aimed at balancing the security and hardware implementation area, using hardware implementation
results for many design decisions, for example field size, representation of field elements, etc.
In the proposed framework, the components of WAGE are used as an example to illustrate different
automation flows and demonstrate the design space exploration on a real-world algorithm
Slide attacks on the Sfinks stream cipher
Sfinks is a shift register based stream cipher designed for hardware implementation and submitted to the eSTREAM project. In this paper, we analyse the initialisation process of Sfinks. We demonstrate a slid property of the loaded state of the Sfinks cipher, where multiple key-IV pairs may produce phase shifted keystream sequences. The state update functions of both the initialisation process and keystream generation and also the pattern of the padding affect generation of the slid pairs
The Music Sound
A guide for music: compositions, events, forms, genres, groups, history, industry, instruments, language, live music, musicians, songs, musicology, techniques, terminology , theory, music video.
Music is a human activity which involves structured and audible sounds, which is used for artistic or aesthetic, entertainment, or ceremonial purposes.
The traditional or classical European aspects of music often listed are those elements given primacy in European-influenced classical music: melody, harmony, rhythm, tone color/timbre, and form. A more comprehensive list is given by stating the aspects of sound: pitch, timbre, loudness, and duration.
Common terms used to discuss particular pieces include melody, which is a succession of notes heard as some sort of unit; chord, which is a simultaneity of notes heard as some sort of unit; chord progression, which is a succession of chords (simultaneity succession); harmony, which is the relationship between two or more pitches; counterpoint, which is the simultaneity and organization of different melodies; and rhythm, which is the organization of the durational aspects of music